Frost dates / By state
Frost dates in New Hampshire
NOAA 1991–2020 normals for a 32 °F freeze. Your own yard can run a little either side.
Short answer
Across 9 NOAA weather stations in New Hampshire, the average last spring frost runs from April 21 at Manchester Airport to May 30 at Berlin Muni Airport. The first fall frost comes as early as September 19 at Berlin Muni Airport and as late as October 19 at Manchester Airport. At 1 of the 10 stations, a freeze can come in any month. Planting zones near these stations run from 4b to 6a.
Find yours by ZIP code
The table below is by weather station. For the station nearest you, and your planting zone, type your ZIP code.
New Hampshire frost dates by weather station
| Station | Last spring frost | First fall frost | Frost-free | Zone nearby |
|---|---|---|---|---|
| Berlin Muni Airport 1,158 ft | May 30 1 in 10 after June 11 | September 19 1 in 10 by September 5 | 112 days | 4b |
| Concord Muni Airport 346 ft | May 8 1 in 10 after May 22 | October 3 1 in 10 by September 21 | 148 days | 5b |
| Durham 2 N 119 ft | May 3 1 in 10 after May 16 | October 10 1 in 10 by September 27 | 160 days | 6a |
| Durham 2 SSW 63 ft | May 7 1 in 10 after May 19 | October 4 1 in 10 by September 23 | 150 days | 6a |
| Jaffrey Muni Airport 1,040 ft | May 5 1 in 10 after May 20 | October 6 1 in 10 by September 25 | 154 days | 6a |
| Lebanon Muni Airport 598 ft | May 9 1 in 10 after May 24 | October 6 1 in 10 by September 23 | 150 days | 5a |
| Manchester Airport 225 ft | April 21 1 in 10 after May 6 | October 19 1 in 10 by October 4 | 181 days | 6a |
| Mt Washington 6,267 ft | A freeze is possible in any month | 5a | ||
| Rochester Skyhaven Airport 323 ft | April 30 1 in 10 after May 13 | October 9 1 in 10 by September 27 | 162 days | 6a |
| Whitefield Mt Washington Airport 1,074 ft | May 27 1 in 10 after June 10 | September 19 1 in 10 by September 8 | 115 days | 4b |
The average date is NOAA's 50% date: half of years have a later last frost, or an earlier first one. Plan by the 1-in-10 date if a freeze would cost you plants. Stations are NOAA's main weather stations, mostly airports. “Zone nearby” is the USDA 2023 zone of the nearest ZIP code within 10 miles. NOAA counts the frost season from August to July, so in the warmest places the “first fall” freeze lands after New Year.
How these dates work
Frost dates come from NOAA's 1991 to 2020 Climate Normals, which work out from each weather station's daily lows how likely the last spring freeze and the first fall freeze (32 °F) are by each date. We use the station nearest the middle of your ZIP code and show its height and distance, since a station on a hill or by a lake can differ from your yard.
The average date is the 50% date: half of years have a freeze after the spring date or before the fall one. The 1-in-10 dates are NOAA's 10% dates, the ones to plan by if a late freeze would cost you plants. Within one yard, cold air pools in low spots while walls and paving hold heat, so some corners freeze before others.
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Where the numbers come from
- USDA Plant Hardiness Zone Map, 2023. Agricultural Research Service, U.S. Department of Agriculture
- PRISM Climate Group, Oregon State University (zone data)
- NOAA NCEI, U.S. Climate Normals 1991–2020, annual/seasonal
- NOAA, Normals calculation methodology (frost-freeze probability dates)
- US Census Bureau, 2025 ZCTA gazetteer (ZIP code centers)